Thursday, December 27, 2012

Printing array values in Java or values of array element in Java would
have been much easier if arrays are
allowed to directly prints its values whenever used inside System.out.println() or format
and printf method, Similar to various classes in Java do this by overriding
toString() method. Despite being an object, array in Java doesn't print any
meaningful representation of its content when passed to System.out.println() or any
other print methods. If you are using array in method argument or any other
prominent place in code and actually interested in values of array then you
don't have much choice than for loop until Java 1.4. Things has been changed
since Java 5 because it introduced two extremely convenient methods for
printing values of both primitive and object
arrays in Java. Arrays.toString(array) and Arrays.deepToString(twoDimensionArray) can print
values of any array. Main difference between Arrays.toString() and Arrays.deepToStringis that deepToString is used to
print values of multidimensional array which is far more convenient than
nesting of multiple for loops. In this Java tutorial we will see 3 different
ways of printing array values in Java or value of element from Array in
Java.

3 ways to print array values in Java

As I said there is no direct way to print values of array in Java if you
directly pass primitive or object array to System.out.println() you will
receive following output:

You can't decipher anything until you are quite familiar of this array
format and even then it doesn't tell anything about contents of array. It just
print type of element and hashcode.
In order to print values of array you can use any of following 3 examples:

Print Array Value Example 1: Using for loop

for
loop is the classical way of printing or displaying values of both one
dimension and multidimensional arrays in Java. before Java 5 you can use array.length to iterate
over all array elements and printing values for each of them. From Java 5
onwards you can use much cleaner enhanced for loop which doesn't require
any counter from moving one element to other in Java. Enhanced for loop in Java
5 is added with other popular language feature e.g. Enum,
Autoboxing
and Generics.
Here is sample code example to print value of element from array using classical
and enhanced for loop in Java:

As you see using enhanced for loop for printing array values is more
concise and clean.

Print Array Values Example 2: Using
Arrays.asList

Arrays.asList() method is used to convert
Array into ArrayList and as you know Collection classes
overrides toString
method to print there contents. By converting array into List we can
leverage that property and print values from ArrayList instead of
Array. Only limitation of this approach is it doesn't print contents of array
if array is of primitive type like int, float or double but
works well if Array contains objects like String. Arrays.asList() is also
used to create
and initialize List in one line. By the way here is simple code example of displaying values form arrayin Java using Arrays.asList() method:

This is by far best and recommended way of printing values from Array in
Java. Only caveat is that Arrays.toString() and Arrays.deepToString() are added
from Java 5 onwards along with other features e.g. Generics,
varargs
or static import.
Use Arrays.toString() method to print both primitive and object single or
one dimension array and use Arrays.deepToString() method to
print values from two dimensional or multidimensional array (array of array in
Java). Here is a simple example of printing array values using Arrays.toString() and Arrays.deepToString() in Java:

Java program to print
array values

Here is the combined examples of printing value of elements from Array in
Java using above three examples. Best way to print elements of Array is to use
new methods added in java.util.Arrays class in Java 5 e.g. toString() and deepToString().

That's all on how to print array values in Java. we have seen three
different example to display contents of array in Java and most easy and convenient approach is using Arrays.toString() and Arrays.deepToString(). if you are
using Java 5.

4 comments
:

Anonymous
said...

I was looking for any easy to print array in Java, didn't know about toString() method of Arrays class. This post gives me lot of insight on How to print array in Java but same time I think Why not use ArrayList in place of array?

currently I'm trying to create a task named Tarski's World... It's a program where you make row and column ( 10x10 ) and then inside the empty array spaces it will generate type of objects with attributes colours and shapes of the objects randomly. ( such as; blue square, red square, red rectangle, green rectangle) .

The generated object n colour will fill all the columns and rows...

I had tried few coding that referring to the internet... but none of it is working properly... need help from you guys...